This invention relates to an operating mechanism for movable parts for the selective closing or exposing of openings, especially for sliding roofs and sliding/lifting roofs of motor vehicles, having a motor drive for the movable part and an actuating member for starting the drive when required.
In the known mechanisms of this type (DE-PS No. 21 00 336 corresponding to U.S. Pat. No. 3,702,430, and DE-PS No. 19 06 084), the actuating member is a switch or a group of switches by means of which the drive can be switched on or off in the desired operating direction. In the case of sliding roofs and sliding/lifting roofs, additional limit switches are provided, as a rule, which stop the movable part (the cover) in the closed position, in the fully retracted position or in a fully tilted-out position. Nevertheless, the operation is awkward. Especially the stopping of the cover in intermediate positions presents problems. For example, in order to bring the cover of a sliding roof from the closed position to a partially opened position, the actuating switch must be pressed and be held in the pressed position until the cover has reached the desired intermediate position. When and whether this is the case, can only be determined by the driver by directly observing the cover, which requires that the driver look away from the road.
The invention is based on the objective of constructing an operating mechanism of the initially described type which can be operated more easily and which permits a precise movement into desired intermediate positions without the requirement of observing the movable part.
According to the invention, this objective is achieved by the fact that the actuating member is formed as a desired-value transmitter for the position of the movable part, and the drive is part of a control circuit which compares the position chosen at the desired-value transmitter with the actual position of the movable part and adjusts the movable part until the deviation has become zero. In the case of the operating mechanism according to invention, the actuating member must only be brought into a position that corresponds to the desired position of the movable part. Via the control circuit, the drive will then automatically be caused to bring the movable part into the desired position and arrest it there. The movable part itself does not have to be observed in this case. A repeated actuating is not necessary, such as was required in the known mechanism, when the switch was released before the desired intermediate position had been reached or after this position had been exceeded. In the case of sliding roofs of motor vehicles or similar devices, any distraction of the driver is avoided.
In order to further facilitate the adjustment, the actuating member advantageously has a selector lever located in the normal field of vision of the operating person to which an indicating device is expediently related so as to show the adjusting range of the movable part. A mechanical catch is also provided, advantageously, that interacts with the desired-value transmitter of its selector lever in order to enable the driver to locate at least one indicated position, such as the closed position of the movable part, without having to look away from the roadway.
The movable part can be given the ability to carry out at least two different types of adjusting movements, such as, in the case of a sliding/lifting roof, to carry out a sliding movement and a pivoting or tilting-out movement. In the case of such a design, a selector switch may be provided for the preselection of the type of adjusting movement and, by means of a single selector lever, the desired position can be selected in the course of all forms of the adjusting movement. Corresponding to a modified embodiment, the design may be such that the type of adjusting movement of the movable part can be selected by the direction of the adjustment of the selector lever with respect to a predetermined starting position. The indicating device is preferably provided with additional elements for indicating the selected type of adjusting movement, and the selector lever may expediently itself, at the same time, form a part of the indicating device. An especially clear indication will be received when the selector lever can be adjusted with respect to one or several fixed wedge representations symbolizing the desired positions.
In accordance with a further feature of the invention, the control circuit has a three-point transfer characteristic with a hysteresis for avoiding an undesired response of the control circuit in the case of slight actual-value/desired-value deviations. The control circuit may have a coarsely regulating and a precisely regulating circuit which may, for example, interact with a motor that can be switched to two different speeds, where the switching from the coarsely regulating to the precisely regulating circuit takes place automatically in order to, among other things, carry out precise positioning.
In this manner, wind forces may be counterbalanced, for example, in the case of a sliding or sliding/lifting roof. A coarse or precise regulating with respect to the position may also take place in connection with a regulating of the motor speed. The desired-value selection and the actual-value detection may basically be selected to be analog or digital. An analog actual-value detection has the advantage that the actual position remains stored, without additional expenditures, even in the case of power failure. Especially suited for an analog desired-value selection and/or actual-value detection are rotary or sliding potentiometers. For a digital actual-value detection, a digital-position transmitter having a count-up/count-down device at the output side is suitable. The control circuit also may be developed to be analog, digital or mixed: analog/digital. Digital-to-analog converters or analog-to-digital converters may possibly be provided in order to permit digital data transmitters to work with an analog control circuit or, vice versa, to permit analog data transmitters to work with a digital control circuit.
In a further development according to the invention, at least one additional transmitter is provided for determining a fixed desired-value, as well as a logic circuit that responds to predetermined conditions for switching from the adjustable desired-value transmitter to the fixed-value/desired-value transmitter. The logic circuit may, for example, respond to the turning-off of the ignition or to a rain sensor in order to automatically bring a sliding or sliding/lifting roof into the closed position. Vice versa, the logic circuit may be actuated by a jamming-protection sensor in order to bring the cover of a sliding or sliding/lifting roof into the end positions of the opening or into one of the end positions of the opening, as soon as, during a cover-adjusting movement, a counterforce is experienced that exceeds the adjusting force that is to be expected normally.
In the case of an arrangement with analog transmitters and a digital signal evaluation, a single analog-to-digital converter may expediently be associated jointly with the transmitters, and the transmitters may be connected to the joint analog-to-digital converter in time-division multiplex operation.
The desired-value transmitter potentiometer may be provided with an additional fixed tap for a signal corresponding to the predetermined starting position. A voltage divider with a resistance that is low in comparison to the combined resistance of the potentiometer may be connected in parallel to such a potentiometer, while the fixed tap of the potentiometer is connected with a voltage-divider tap for the starting-position signal in an electrically conductive manner. Such a design results in a particularly simple mounting and permits a simple adaptation of the characteristic adjusting line to the respective requirements.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.